Dare to Compare your Rations


How are forages evaluated for their nutrients?

Twenty years ago, silages were treated as sources of protein, fibre and starch, with degradability (the rate at which the forage is digested in the rumen) being assessed from a table. More modern ration formulation tools have methods of assessing the digestibility of an actual sample, with many using the neutral detergent fibre digestibility (NDFD) approach to estimate how much energy your forage will provide. Using this approach, a sample of the forage is incubated in rumen fluid for up to 72 hours although duration varies depending on the model. This allows the impact on energy to be estimated, since the more that is digested, the more energy is available.

However, taking a single time point is not the most sensitive way to estimate fibre degradation. This is because the fibre breaks down in a curvilinear fashion; starting rapidly and slowing down with time (see Graph 1). When a single time point is chosen, it makes it harder to determine the true value.

However, the Trouw Nutrition/Shur-Gain approach uses eight time points to generate a curve, allowing greater accuracy in determining the energy supply from a forage. This improved system means that rations can be more accurately tailored to the actual forage on the farm.


When rations are balanced for a specific milk yield, the energy and amino acids needed to meet that milk yield are calculated (based on an assumed degradation in the rumen). In Newton®, requirements are calculated based on a representative cow, using milk production, % fat and % protein, average weight, days in milk, lactation number and dry matter intake of the group of cows for which we want to balance the ration. This cow needs to be as close as possible to reality but generally with a higher milk production than the group average, so that higher producing cows in the group are adequately fed. The selected ingredients are then least cost formulated so that the milk will be produced at the lowest cost. That all makes perfect sense, but can be affected by how much higher the requirements are versus actual milk production. If that amount of milk is too high, then the cost of the ration will be high, meaning the income over feed cost will be lower.

Over the years, we have noticed that in circumstances where the milk yield is high, a small decrease in the milk yield can result in cost reductions of several cents per day – when the program can select less of an expensive ingredient to meet requirements.

In Newton, we have developed a function that looks at the potential savings (or benefits) by looking at decreasing or increasing the requirements, which allows your Nutrition Advisor to determine if there is money being left on the table.


Newton is designed to provide accurate levels of rumen available carbohydrate and reduce waste from overfeeding. Extensive research conducted at the Trouw Nutrition Agresearch facility and on farms throughout Canada and the US has demonstrated that significant feed savings can be expected from improved ration accuracy with high quality forages.